Gauss strength is measure of magnetism named after the German mathematician Karl Friedrich Gauss ( 1777–1855 ), who applied mathematical principles to magnetism.
The gauss rating of a magnet determines the speed in which it works, and the thickness determines the depth of penetration. Some magnet companies list their products by internal gauss, not the external gauss rating. A quick rule of thumb in determining proper gauss strength is take the external gauss rating and multiply this number by 3.9. So, a 600 gauss external strength rated magnet can also be called a 2,340 gauss internal strength rated magnet. It is important that you are not misled into believing you're getting a higher strength product, as both are correct ratings for the same magnet.
Gauss strength can be misleading, as the strength of the magnetic field falls off very quickly as the distance from the surface of the magnet increases. Depending upon the strength, size, and distance from the skin, actual gauss strength inside the human tissue can be much less than the gauss rating of the magnet. If the magnet is to penetrate deep into the body, it will need to be stronger. To act one inch deep, it should be a 700 to 1000 gauss external strength rated magnet. For two inches deep a 1200 to 2000 gauss external strength rated magnet is best.
It is important to note that the material of a magnet alone does not determine its strength. It is a combination of material (strength) and mass (size). To illustrate, lets take one neodymium magnet (12,000 gauss) and one ceramic magnet (4,000 gauss). If both magnets are the same size, the neodymium will have the stronger field, because it has a larger gauss rating.
Now let's assume that the same neodymium magnet has a 1/2" diameter and 1/8" thickness, and the ceramic magnet a 3/4" diameter and 1/4" thickness. Even though the neodymium magnet is rated 12,000 gauss and the ceramic is 4,000 gauss, the ceramic magnet will have the stronger field. Why? Because, its greater mass helps to produce a stronger field.
In most clinical studies the best results are achieved with a magnetic field of 500 to 600 gauss within the tissue, which often requires a much stronger magnet to deliver that amount of energy within the body itself. The depth of penetration of the magnetic field appears to be at least as important as its strength. This is extremely important. The larger the mass of the magnet, the stronger and more effective it will be. If the magnets are too small, the magnetic field will drop below therapeutic levels before it even reaches the injury site. Magnets made from Neodymium (a rare earth metal), commonly called Rare Earth Magnets, are unusually strong in relation to their size, and therefore believed to have the deepest penetrating fields. Some people may have a skin reaction to direct exposure to some Rare Earth Magnets. For this reason, many therapeutic magnets are plated with gold or other non-reactive metal, or contained within a wrap or magnetic mattress pad.
Note: If you come across a product that simply states gauss strength without stating that it is the surface or external rating, divide the value of the product by 3.9. For example a 10,500 manufacturers rating for a neodymium magnet, will measure approximately 2,690 surface gauss using a digital gauss meter (which is a very accurate instrument).
Something else to be aware of is that gauss strength is not cumulative. In other words if each magnet has a manufacturers gauss rating of 3,000 and there are 10 magnets in the product, the strength is still 3,000 gauss, NOT 30,000 gauss. Although, more magnets in a products means that the magnets are spaced closer together, creating a more uniform magnetic field. The number of magnets needed to create a consistent field is also dependent upon the size of the magnets. As stated previously, larger magnets will create larger fields. The key is that you do not want large spaces between the magnets, as large spaces will create empty gaps in the magnetic field, in which there is no therapeutic benefit.
